droos02800
droos02800
2018-06-07 02:35

从SQL表中获取以前的记录

已采纳

I figure out how I can get the next adid using this:

$sql_next = "SELECT adid FROM table WHERE adid > $current_adid ORDER BY adid 
LIMIT 1";
if ($result = $mysqli->query($query)) {
while ($row = $result->fetch_assoc()) {

$next = $row['adid'];

echo '<a href="https://someurl.com/'.$next.'">Next</a>';

}
}

However, I am not sure how to get the previous adid. I tried changing WHERE adid < $current_adid but it didn't do the trick. What should I use to get a previous record from the SQL table?

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1条回答

  • duanchi8112 duanchi8112 3年前

    You need to reverse more than just the comparison:

    SELECT adid
    FROM table
    WHERE adid < $current_adid
    ORDER BY adid DESC
    LIMIT 1;
    

    The ORDER BY direction also needs to be reversed.

    You could also replace these with:

    SELECT MIN(adid)
    FROM table
    WHERE adid > $current_adid;
    
    SELECT MAX(adid)
    FROM table
    WHERE adid < $current_adid;
    

    The aggregation functions might make the logic clearer.

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